precise format of .authinfo file

[dmahler]

I would like to know the exact specification of the .authinfo file format.

I am trying to use gnus to read my mail.
I now have a configuration that works for both
my personal gnail and my work office365 accounts
as long as I supply the passwords manually.

I am trying to create an ~/authinfo.gpg to automate logging in.
Initially I am trying to set up a plain ~/.authinfo file
to eliminate gpg related issues and I am only doing it for my gmail account.

When I supply a ~/.authinfo file for my gmail account
I am no longer asked for a password
but my gmail mailboxes do not appear
and in *Messages* I get a the message:

    Warning: Opening nnimap server on gmail.com...failed: BAD Failed to parse 
your command f189mb236504406ivf

I get a similar problem for my work email when I try to set up authinfo for 
that account.

The format of authinfo entries is usually given as

machine HOST login ACCOUNT password PASSWORD port PORT

where the lowercase words are literals and upper case words get substituted by 
concrete values.
An example would be:

machine imap.gmail.com login mr-x@gmail.com password H0keyPok3ey port 993

However in some examples either ACCOUNT and/or PASSWORD are sometimes shown as 
quoted, eg:

machine imap.gmail.com login "mr-x@gmail.com" password "H0keyPok3ey" port 993

It is also not clear if any character escaping needs to be done.

Usually the ACCOUNT is given as the full email address.

Sometimes the port is given by a symbol like "imap" or the port section is 
omitted altogether.

I would also like to make sure that the entries are indeed space separated and 
not tab separated.

I have tried a number of the above possibilities alone and in combination
and all with the same result as above.

I am using GNU Emacs 25.2.

What do I need to get gnus to work with the authinfo.